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Controlling the selectivity–stability tradeoff in zeolite catalysis: oligomerization–alkylation, cracking, and methanol-to-hydrocarbons 


    Problem Statement

    Olefins and aromatics are commodity chemicals used in producing plastics (in the petrochemical industry), lubricants, plasticizers, and surfactants, among other products. However, there is an imbalance between their production and demand, which reactions like oligomerization, alkylation, and cracking over zeolites could help address. At the same time, zeolites serve as excellent catalysts for converting methanol to hydrocarbons (MTH), olefins (MTO), or aromatics (MTA). These processes aim to produce light hydrocarbons such as propylene or to convert ethylene into higher-value alpha-olefins, aromatic hydrocarbons (BTX), and jet fuel.


    Our focus in this project is to synthesize, modify, and develop new catalysts with engineered porosity at multiple scales: from hierarchical and hollow zeolites to catalytic particles, bodies, or technical catalysts intended for implementation. Additionally, we incorporate various metals (e.g., Ni, Cr, Zn) to influence the selectivity toward the desired products.

    We utilize various reactors, including forced dynamic, operando, high-throughput packed-bed, and batch reactors.

    OLG-O2H

    Goals

    • Control the catalyst structure to balance selectivity and stability.
    • Metal modulation: Use Ni, Cr, Zn to bias reaction pathways and improve selectivity to target hydrocarbons.
    • Deactivation control: Reduce coke formation and extend catalyst lifetime with regeneration strategies.
    • Reactor optimization: Shape catalysts into bodies/extrudates and validate 100 h continuous stable operation.

    Related People

    Faseeh Kulangara Kandiyil
    Hend Omar Mohamed
    Kiruthika Jayaseelan

    Related Publications

    A Zeolite-Based Cascade System to Produce Jet Fuel from Ethylene Oligomerization

    by Mohamed, Abed, Zambrano, Castaño, Hita
    Ind. Eng. Chem. Res. Year: 2022 DOI: https://doi.org/10.1021/acs.iecr.2c02303

    Abstract

    Jet fuel production from ethylene oligomerization opens a sustainable pathway to clean sulfur-free fuel that is increasingly in demand due to the potential renewable origin of ethylene. The key to a viable heterogeneously catalyzed process is to improve the selectivity of the jet fuel while prolonging the catalyst lifetime. To this end, we have assessed and optimized a dual-bed cascade system based on a dimerization bed that is followed by an oligomerization bed using Ni supported on Y zeolite and ZSM-5 zeolite catalysts, respectively. Our optimization approach uses different catalyst acidities, temperatures, and bed configurations for determining the best yield–conversion relationship. Under optimized dual-bed conditions, we can produce 64 wt % of jet fuel at the beginning of the reaction and maintain a 50 wt % selectivity of this fraction for over 20 h on stream. This paper also analyzes coke deposition (content and nature) at the different experimental conditions and catalyst bed arrangements using temperature-programmed combustion. We demonstrate that the dual-bed approach is effective for protecting the main oligomerization bed (ZSM-5 catalyst) from deactivation, leading to the formation of a lighter type of coke compared with that using the initial Ni2+ HY-based dimerization catalyst, which deactivates at a faster rate.

    Keywords

    OLG HCE CRE